U.S. Pat. No. 4,939,120 illustrates a magnetic bearing employing a type 2 superconductor that employs one of the high temperature superconducting ceramic materials. This patent illustrates various forms of magnetic bearings.
Another reference is "Magnetic Forces in High-T.sub.c Superconducting Bearings" by F. C. Moon, published in Applied Electromagnetics in Materials, 1 (1990) 29-35 Elsevier. This paper discloses various drag effects on the magnetic bearings including that of irregularities in the magnetic field. FIG. 3 indicates no dependence of angular frequency decay rate on pressure.